Homogeneity of the 16S rDNA sequence among geographically disparate isolates of Taylorella equigenitalis

Background

At present, six accessible sequences of 16S rDNA from Taylorella equigenitalis (T. equigenitalis) are available, whose sequence differences occur at a few nucleotide positions. Thus it is important to determine these sequences from additional strains in other countries, if possible, in order to clarify any anomalies regarding 16S rDNA sequence heterogeneity. Here, we clone and sequence the approximate full-length 16S rDNA from additional strains of T. equigenitalis isolated in Japan, Australia and France and compare these sequences to the existing published sequences.

Results

Clarification of any anomalies regarding 16S rDNA sequence heterogeneity of T. equigenitalis was carried out. When cloning, sequencing and comparison of the approximate full-length 16S rDNA from 17 strains of T. equigenitalis isolated in Japan, Australia and France, nucleotide sequence differences were demonstrated at the six loci in the 1,469 nucleotide sequence. Moreover, 12 polymorphic sites occurred among 23 sequences of the 16S rDNA, including the six reference sequences.

Conclusion

High sequence similarity (99.5% or more) was observed throughout, except from nucleotide positions 138 to 501 where substitutions and deletions were noted.     

A translational enhancer element on the 3'-proximal end of the Panicum mosaic virus genome

Panicum mosaic virus (PMV) is a single-stranded positive-sense RNA virus in the family Tombusviridae. PMV genomic RNA (gRNA) and subgenomic RNA (sgRNA) are not capped or polyadenylated. We have determined that PMV uses a cap-independent mechanism of translation. A 116-nucleotide translational enhancer (TE) region on the 3'-untranslated region of both the gRNA and sgRNA has been identified. The TE is required for efficient translation of viral proteins in vitro. For mutants with a compromised TE, addition of cap analog, or transposition of the cis-active TE to another location, both restored translational competence of the 5'-proximal sgRNA genes in vitro.     

Docosahexaenoic and Eicosapentaenoic Acids Segregate Differently between Raft and Nonraft Domains

Omega-3 polyunsaturated fatty acids (n-3 PUFA), enriched in fish oils, are increasingly recognized to have potential benefits for treating many human afflictions. Despite the importance of PUFA, their molecular mechanism of action remains unclear. One emerging hypothesis is that phospholipids containing n-3 PUFA acyl chains modify the structure and composition of membrane rafts, thus affecting cell signaling. In this study the two major n-3 PUFA found in fish oils, eicosapentaenoic (EPA) and docosahexaenoic (DHA) acids, are compared. Using solid-state (2)H NMR spectroscopy we explored the molecular organization of 1-[(2)H(31)]palmitoyl-2-eicosapentaenoylphosphatidylcholine (PEPC-d(31)) and 1-[(2)H(31)]palmitoyl-2-docosahexaenoylphosphatidylcholine (PDPC-d(31)) in mixtures with sphingomyelin (SM) and cholesterol (chol). Our results indicate that whereas both PEPC-d(31) and PDPC-d(31) can accumulate into SM-rich/chol-rich raftlike domains, the tendency for DHA to incorporate into rafts is more than twice as great as for EPA. We propose that DHA may be the more bioactive component of fish oil that serves to disrupt lipid raft domain organization. This mechanism represents an evolution in the view of how PUFA remodel membrane architecture.     

Bluetongue virus serotype 8: abortion and transplacental transmission in cattle in the Burgundy region, France, 2008-2009

During the incursion of bluetongue virus (BTV) serotype 8 in France in 2007, an increase in the number of abortions in cattle was observed, but the cause was not clearly established. A survey of all the reported cases of abortion in cattle from November 2008 to April 2009 was conducted in the Nièvre district (Burgundy region) to determine the percentage of abortions as a result of BTV-8 and to study factors that could have played a role in BTV-8 transplacental transmission. BTV-8 was present in 16% of the fetuses or newborn calves that died within 48 h, from 780 dams. Dams inseminated before the BTV epizootic peak recorded from July to September 2008 were more likely to have BTV-positive abortions (OR=5.7, P<0.001) and those vaccinated in May or June 2008 were less likely to have BTV-positive abortions (OR=0.3, P=0.01 and OR=0.4, P=0.001, respectively). The gestational month was not a predictor of BTV abortion. In blood or spleen, fetuses/calves from RT-PCR-positive dams had significantly higher RNA concentrations than fetuses/calves from RT-PCR-negative dams. Of the 128 dams that had BTV-positive fetuses or calves, 60% were RT-PCR-negative. BTV-8-positive fetuses/calves were significantly more frequent (n=42 vs n=21, P=0.082) amongst those showing clinical signs or lesions suggestive of cerebral damage.     

Temporal Variation in Seed Predation by Insects in a Population of Syagrus romanzoffiana (Arecaceae) in Santa Catarina Island, SC, Brazil

Insect seed predation may vary depending on seed production. The present study considers the hypothesis that the rates of seed predation tend to be smaller in years of higher fruit production. Thus, we monitored the production of fruits and predation of seeds of the palm Syagrus romanzoffiana over 2?years in the Atlantic Forest (Parque Municipal da Lagoa do Peri, Florianópolis, SC, Brazil), between July 2006 and June 2008. Plots of 0.25?m² were fitted under 20 mother plants and fruits were monthly collected for assessment of abundance and seed predation. There was variation in fruit production between the 2?years and among reproductive plants. Predation rates were high and occurred in the predispersal phase by the Curculionidae Revena rubiginosa Boheman, Anchylorhynchus aegrotus Fahraeus, and Anchylorhynchus variabilis Gyllenhal. Seed predation by these species of Anchylorhynchus is first registered in the present study. In average, about 60% of the seeds monthly produced in the population tend to escape insect predation in year of high or low production, becoming available for recruitment. The predation rate was not related to the amount of fruits produced per reproductive plant. Also, different than expected, there was a positive relation between the rates of seed predation and the total of fruits produced monthly on the plots. Thus, no evidence for the satiation of insect seed predators was found in this study with S. romanzoffiana.     

Long-term mutagenic effects of ionising radiation on mice which vary in their p53 status

The tumor suppressor gene p53 plays a major role in the maintenance of genomic integrity. The impact that variations in cellular turnover rates and sensitivity to DNA damage will have on the effectiveness of p53 in this role was examined by following the induction and persistence of mutations in the brain and small intestine of mice after exposure to ionising radiation (IR). The examination of mutagenesis was carried out using the pUR288 LacZ plasmid-based mouse model-consisting of mice containing a target gene for mutation analysis integrated into every cell. In addition the mice varied in their p53 status. The tissues were compared at post-irradiation time-points from 24h to 3 months. The mutation frequencies (MFs) in the p53 wildtype and heterozygous brains peaked at 24h post-irradiation, and then returned to background or close to background levels, respectively. The p53 nullizygous brain showed a more fluctuating MF pattern, but returned to background levels by 3 months, indicating that the effect of the loss of p53 did not result in lasting differences in the response to mutation induction in the brain. In the intestine, there was a different pattern; in the wildtype and heterozygous animals, the MFs increased from 24h to a peak at 4 weeks post-irradiation, before decreasing towards background levels at 3 months. The MFs in the intestine from the nullizygous animals did not decrease significantly between 4 weeks and 3 months, illustrating that the loss of p53 had a greater impact in this tissue than the brain. The variation in mutation frequencies and the type of mutations generated after DNA damage suggests that while p53 plays a significant role in the maintenance of genomic integrity, other mechanisms, such as the drive to replicate in progenitor cells, can reduce its effectiveness as the "guardian of the genome".     

Facies development of a Late Ordovician mixed carbonate-siliciclastic ramp proximal to the developing Taconic orogen: Lourdes Formation, Newfoundland, Canada

The Upper Ordovician (late Whiterockian to Mohawkian) Lourdes Formation represents a narrow (tens of kilometers), short-lived [∼5–7 million years (my)], open-ocean (high-energy) mixed siliciclastic-carbonate ramp that onlapped allochthonous strata along the orogen side of the local Taconic foreland basin. Platform development followed a 6–8 my hiatus during which weathering had concentrated chemically mature siliciclastics that were admixed with initial carbonate sediments. A cross-platform facies gradient contains paleokarst and peritidal carbonates and sandstones, shallow-ramp carbonate bioherms and skeletal shoals, and deeper ramp calcareous shales. Transgressive systems tracts are marked by ramp-wide sheets and shoals of skeletal grainstone and low accumulation rates, and highstand systems tracts are marked by significant admixture and interbedding of siliciclastics with cross-ramp carbonate facies. Platform demise coincides with increased siliciclastic input, which is likely tectonically influenced. The Lourdes platform is equivalent to epicontinental foreland ramps along eastern Laurentia, but its narrower width precluded formation of oceanographically restricted platform-interior facies.     

Continuous plankton records stand the test of time: evaluation of flow rates, clogging and the continuity of the CPR time-series

The Continuous Plankton Recorder (CPR) survey is one of themost extensive biological time-series in existence and has beenin operation over major regions of the North Atlantic since1932. However, there is little information about the volumeof water filtered through each sample, but rather a generalassumption has persisted that each sample represents 3 m³. Datafrom electromagnetic flowmeters, deployed on CPRs between 1995and 1998, was examined. The mean volume filtered through sampleswas 3.11 m³ and the effect of clogging on filtration efficiencieswas not great. Consequently, even when the likely variationsin flow due to clogging are taken into account, previously identifiedlinks between zooplankton abundance and climatic signals remainstrong.     

Detection of diaminobenzidine reactions using scanning laser confocal reflectance microscopy

We used scanning laser confocal microscopy to visualize sites of peroxidatic activity as detected by the diaminobenzidine (DAB) reaction. Imaging was achieved by employing the reflectance mode of this instrument. Intense reflectance was detected after DAB localization of endogenous granule-associated myeloperoxidase in neutrophils and of the exogenous tracer horseradish peroxidase in mouse oocytes. Detection of DAB reaction products with confocal reflectance microscopy will probably be an important addition to the utility of this cytochemical technique.